Conventional practice encompasses a heat-transfer technology, in which the colorant is not sprayed, but deposited and fixed on a surface to be printed, by means of resistors incorporated into a thermal printing head which heats a ribbon coated with colorants by using a modulated electric current.
The conventionally-used machines which implement this technology generally print either in black and white or in color, by effecting a first run when the front of the card is printed and a second run with the card reversed to print the back side, after the machine has been reprogrammed. This type of machine is slow and requires intermediate manual operations.